Cause Analysis And Treatment Measures Of Collapse In No.1 Tunnel Of Wangjiazhai Tunnel

With the continuous development of the western development,Chinese western hills and alpine canyons in the construction of a large number of highways at the same time encountered many difficult,long mountain tunnel,also encountered many complex problems.Tunnel rock and rock collapse is the tunnel construction is one of the most common geological disasters,the tunnel construction personnel,equipment has a very serious threat.In this paper,the landslide accident occurred in the construction of the right line of Wangjiazhai No.1 tunnel in the Maerkang section of the Wenma railway is taken as the research object.Based on the theoretical research,the field monitoring and the FLAC3 D numerical simulation analysis,the engineering geology,hydrogeology and construction factors And so on.The causes of tunnel collapse accidents are analyzed.According to the causes and characteristics of landslide accident formation,the corresponding treatment method is established,and finally the effect of landslide treatment is analyzed and evaluated.The main contents of the thesis include the following:(1)Based on the analysis of the failure mechanics of the surrounding rock,the failure modes of different layered rock mass and the rock mass stability are analyzed theoretically,and the slip failure of the layered rock is briefly discussed.(2)Through the analysis and research on the monitoring data of Wangjiazhai No.1 tunnel,the variation law of surrounding rock displacement during the formation of landslide accident is analyzed and summarized.It can be concluded that the deformation of the surrounding rock after the initial support is longer,Coupled with the development of groundwater,creep phenomenon is prominent,especially in the early support is not timely,improper early structure and late reinforcement measures in the case of the surrounding rock deformation will continue to increase.(3)The finite difference software FLAC3 D is used to simulate the typical landslide section of the tunnel,and the three-dimensional numerical simulation analysis of the landslide section is carried out.The simulation results are analyzed in detail.Through the engineering geological conditions,hydrogeological conditions,supporting technology,Construction methods and other factors on the cause of the collapse of the accident were a comprehensive discussion,the conclusions are as follows:(1)Based on the numerical simulation of the typical landslide section,it is concluded that there are significant stress relaxation and stress concentration in the surrounding rock,especially in the vicinity of the arch,after the tunnel excavation and the initial branch,and the upper and lower part of the left and right wall And the shear stress zone is formed in the lower left of the arch,and a small range of tensile stress is formed.The 45 ° range is the maximum displacement position.(2)The fluid-solid coupling analysis of the section under seepage is studied.It is found that the influence of groundwater on the stability of surrounding rock is stronger.Under the action of underground,the stress field or displacement field of tunnel Abnormal deformation,which is due to the tunnel section of the surrounding rock broken and thin layer,under the action of groundwater creep phenomenon is obvious,the final support can not support such a large deformation and the formation of landslides.(3)Through the numerical simulation of the collapse section,the "space effect" of the face of Wangjiazhai No.1 tunnel is about 15 m,and the distance between the lining and the face of the tunnel is much more than 15 m,The surrounding rock of the section has lost the protection of the "space effect" of the face,and the deformation caused by the collapse section is controlled by the rheological property of the groundwater for too long.The imbalance of the tunnel construction process is Leading to Wangjiazhai No.1 tunnel to produce landslide disaster important reason.(4)Through the analysis and research on the causes and characteristics of the landslide in Wangjiazhai No.1 tunnel,the measures to deal with the landslide disaster are determined,and the arching settlement,horizontal convergence and surrounding rock pressure data are detailed.The treatment and analysis of the collapse of the effect of a reasonable assessment,that governance measures are good.